#28397 [Bgs]: call-by-value on objects doesn't work

[bobalong at gmx dot net]

 ID:               28397
 User updated by:  bobalong at gmx dot net
 Reported By:      bobalong at gmx dot net
 Status:           Bogus
 Bug Type:         Scripting Engine problem
 Operating System: Redhat 9
 PHP Version:      4.3.4
 New Comment:

Look - like I said before, the reproduce script is as short as I can
make it. It's not difficult to get your head around, so if you can't be
bothered to take the time then that's your issue. I'm aware of your
rules regarding reproduce scripts, but due to the deep-seated nature of
the problem, in this case I hold that the reproduce script I submitted
is readable and usable.

I'm sure anyone who cares about objects in PHP4 would be interested in
this bug, but like I said in my last post, I would imagine at most of
those people have moved to PHP5 by now.

Keep up the good work!


Previous Comments:
------------------------------------------------------------------------

[2005-02-15 01:52:15] [EMAIL PROTECTED]

Okay, so let's close this report until someone (you?) is able to
provide a shorter and more readable reproduce script, that clearly
decribes the problem.

------------------------------------------------------------------------

[2005-02-12 11:56:18] bobalong at gmx dot net

Just to clarify, this is NOT a ZE2 bug - my mistake. I can't make the
reproduce script much shorter than it is, as it involves class
definitions and client code. I could remove the comments, but that's
not really what you're talking about, right?

Personally I've moved to PHP5 and found the object model to be
absoultely fine. If I were working on PHP4 bugs I would rationalise
that anyone looking for this kind of (fairly) advanced OO behaviour
would probably be using PHP5 by now anyway.

Cheers
Rob

------------------------------------------------------------------------

[2005-02-11 20:34:12] [EMAIL PROTECTED]

Please provide a *short* but complete reproduce script.
Also, I don't get why it's a ZE2 bug if you're using 4.3.x.

------------------------------------------------------------------------

[2004-05-14 13:59:49] bobalong at gmx dot net

Description:
------------
I've created a user-defined list type - a bit like the ubiquitous
ArrayList - and wrapped it in another class, which exposes part of the
internal list's interface... OK, so nothing radical so far.

My problem is that when I make use of the list's exposed interface in
the wrapper class, it becomes a reference type for no apparent reason.

Another consequence, due to a previous bug
(http://bugs.php.net/bug.php?id=20993), is that if I pass the wrapper
object to a function that modifies the internal list, the original
object gets modified too, as though I'd passed it by reference!


Reproduce code:
---------------
<pre>
<?
        //define a user type, similar to an ArrayList
        Class MyList
        {
                var $internalArray = array();

                function Add($obj)
                {
                        array_push($this -> internalArray, $obj);
                }

                function Remove($index)
                {
                        unset($this -> internalArray[$index]);
                }
        }

        //create a wrapper for the above list
        Class MyListWrapper
        { 
                var $myList;

                function MyListWrapper()
                {
                        $this -> myList = new MyList();
                }

                function AddItem($item)
                {
                        $this -> myList -> Add($item);
                }

                function RemoveItem($index)
                {
                        $this -> myList -> Remove($index);
                }
        }

        //function that modifies the wrapper's internal list
        function UpdateListWrapper($listWrapper)
        {
                $listWrapper -> RemoveItem(0);
        }

        //1. create a new wrapper object and dump
        $listWrapper = new MyListWrapper();
        var_dump($listWrapper);

        //2. now add item to wrapper object and dump
        $listWrapper -> AddItem("id");
        var_dump($listWrapper); //notice the list is now a reference type

        //3. now pass to modification function
        UpdateListWrapper($listWrapper);

        //4. see the original has been modified, as if 
        //   call-by-reference had been used
        var_dump($listWrapper);
?>
</pre>

Expected result:
----------------
object(mylistwrapper)(1) {
  ["myList"]=>
  object(mylist)(1) {
    ["internalArray"]=>
    array(0) {
    }
  }
}
object(mylistwrapper)(1) {
  ["myList"]=>
  object(mylist)(1) {
    ["internalArray"]=>
    array(1) {
      [0]=>
      string(2) "id"
    }
  }
}
object(mylistwrapper)(1) {
  ["myList"]=>
  object(mylist)(1) {
    ["internalArray"]=>
    array(1) {
      [0]=>
      string(2) "id"
    }
  }
}


Actual result:
--------------
object(mylistwrapper)(1) {
  ["myList"]=>
  object(mylist)(1) {
    ["internalArray"]=>
    array(0) {
    }
  }
}
object(mylistwrapper)(1) {
  ["myList"]=>
  &object(mylist)(1) {
    ["internalArray"]=>
    array(1) {
      [0]=>
      string(2) "id"
    }
  }
}
object(mylistwrapper)(1) {
  ["myList"]=>
  &object(mylist)(1) {
    ["internalArray"]=>
    array(0) {
    }
  }
}




------------------------------------------------------------------------


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Edit this bug report at http://bugs.php.net/?id=28397&edit=1